STANDARD CLASSES SHIPS - ibiblio

DECLASSIFIED IAW DOD UZ:W OF 3 MAY 197~., SUBJ":

DECLASSIFICATION OF WWII fillCORDS

I STANDARD CLASSES of JAPANESE MERCHANT SHIPS . Contains drawings, characteristics, and names of merchant vessels being constructed in quantity by the Japanese.

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Division of Naval Intelligence

January 1945

0 N I 208-J (Revised)

Supplement 3

May be incorporated in the basic manual provided classification is maintained

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JAPANESE STANDARD MERCHANT SHIP CONSTRUCTION

In the latter part of 1943 and during 1944, a quantity of new and unknown Japanese merchant ships have been observed, many of them radically different in design from the fast, modern vessels of the pre-war era. Sufficient numbers of the same type of ship have been noted to permit the formation of definite conclusions as to the amount and character of stsndardization accomplished in Japanese wartime merchano ship construction. In addition, recent captured documents have listed the types adopted as standard and outlined sufficient characteristics to make possible the identification of individual classes.

Pre-war Construction The unusual features of these new vessels can best be illustrated by com-

parison with the character of pre-war shipbuilding in Japan. Prior to 1941, no actual and effective standardization had been accomplished; for, while shipbuilding was subsidized by the government, design wa.s largely determined by the shipping concerns or builders. The nature of Japan's merchant marine activities before the war dictated specifications in ship design which resulted in a standardization of general types as opposed to the adoption of an individual design. This has made possible the formulation of the JMST system of reporting Japanese vessels, a method which recognizes the similarity in characteristics of vessels within a given tonnage range. Freighter design on the whole was concentrated in Diesel-powered ships averaging 6,000 gross tons, with streamlined superstructure amidships, cruiser sterns, and with hulls built for speed. Few engines-aft cargo carriers were constructed outside of the AMAKASU MARU NO. 1 class of 1,900 gross tons, of which about 40 were built before the war. Tanker design tended to 10,000-ton ships with speeds of 17 knots normal cruising and 20 knots maximum-mostly fitted with Diesel engines. It is interesting to note that in the 6 years prior to the outbreak of war approximately 330 ships of over 1,000 tons were built, involving over 100 different classes; 18 of these classes were composed of 5 or more ships, but in only 2 were more than 10 built. At variance with this

pre-war record is the tendency in new construction to adopt a few individual designs and to produce as great a quantity of these as construction facilities and possible use of mass production methods will allow.

Wartime Design With her sea lanes enonuously extended soon after the outbreak of war, and

with the successful activity of United States submarine patrols becoming obvious, Japan must have foreseen the inroads which would be made upon her supply of merchant vessels. Since approximately 2 years are required to design 'and initiate construction on standard types of ships, work was apparently begun on the radically new designs early in 1942; for it is believed that they did not begin coming off the ways until the early spring of 1944. Between the fall of 1941 and the start of construction on the now types shipbuilding is thought to have continued along the lines of the older designs; for, of the nine standard classes so far identified, two are almost identical with pre-war design, and two, a.lthough never before observed, show no radical change in design characteristics. It should also be remembered that between 7 December 1941, and 1 July 1944, approximately 125 ships of nonstandard construction totaling 430,000 gross tons have been built. Construction of vessels of individual design will undoubtedly continue, to a limited extent, in the future.

In the preparation of de"signs for new ships, especially standard designs from which vessels are to be built in quantity, consideration must be given the requirements of the ship itself, such as speed, cargo capacity, range, etc., and the wartime facilities for construction including speed of construction, availability of various types of engines, facilities for casting or forging parts, and the like. In the new Japanese designs, cargo capacity and speed of construction have been given paramount consideration at a considerable sacrifice in the speed of the ships themselves.

A glance at the drawings includeo in the oiscussion of individual types which follows will show the emphasis which has been placed on engines-aft design.

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DECLASSU'IED IA'.'/ DOD MZ:!:O OF 3 MAY 1972, SUBJ:

n~r.LASSlFICATION "''ttl'1'"2b1i- J Supplemen t 3

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.WWII

RECOEDS

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DIVISion of Naval Intelligence

All but two of the standard classes so far identified are of engines-aft r.onstruetion. While this is a logical type for economical operation, it may also indicate a shortage of facilities for forging the longer propeller shafts needed in vessels with engines amidsh ip.

Typical of the new hull design is its angularity and its broad beam in relation to length. The latter is particularly apparent when compared with vessels of the pre-war period, and again is an indication of the need for large carrying capacity at a sacrifice in speed. The hull shape suggests the adoption of flat as opposed to curved surfaces throughout the vessel, which increase the rapidity and ea~e of construction, even by inexperienced builders. This design can easily be noted in the photograph which accompanies the description of Type E being mass-produced at Wakamatsu. In the discussion of individual types which follows, the word "economy" has been adopted as descriptive of this shape of hull.

It is interesting to note that in all caBes where captured statistical data can be ascribed with relative certainty to observed design, the term" Modified" has applied to vessels with "economy" hull shapes. Cruising speeds specified for the various types are a further indication, since those for the regular types are consistently 2 to 3 knots higher than those for the Modified classes. From this it may be assumed that the designs for Types A, B, C, D, E, TL, TM, and TS are of normal construction. Designs with economy hulls have been identified for Type A (Modified), D (Modified), E (Modified), and TM (Modified). Additional "economy" designs have been observed which closely approximate most specifications for Types B and TS. These are, in all probability, later modifications which were either in the experimental stage or not as yet adopted at the time the captured statistics were issued by the Japanese.

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The general use of steam turbine and reciprocating engines instead of Diesel, which were in common use before the war, is another noteworthy feature of the standard types. ln all probability this indicates a shortage of facilities for building the more complicated Diesel engine, and also denotes foresight on the part of the Japanese in that they may in the future be forced to depend on coal rather than oil for fuel. Among the standard types, Diesels are being used only in vessels under 1,000 gross tons (Types E and F) .

Individual Types The standard types outlii,ed on the following pages include profile drawings

and photographs where they can be assigned, notes on distinctive features which will lead to rapid identification, all known statistical information, and, where possible, names of vessels belonging to the class. Some of the types have not, as yet, been identified; it is possible that certain of the classes, such as Type A (Cargo) and TL (Tanker) were never placed in quantity production. Several of the profiles have been drawn from vertical photographs only and should be considered tentative. Note also that ship names listed for standard types include vessels built up to 1 July 1944, and have been selected from known construction on the basis of types, tonnage, and year built. Their assignment, therefore, should not be considered positive. In addition to the statistical data included under each type, all classes above 1,000 gro~~ ton~ are believed to carry four depth charges. Profile drawings have been graded A, B, C, and D to indicate their evaluated accuracy.

This summary has been prepared by the Division of Naval Intelligence. Extensive use has been made of ''Weekly Intelligence" Bulletin No. 12 published by CIN CPAC-CIN CPOA, and of Shipping Report No. 11 prepared by the Shipping Center, U. S. Naval Unit, 14th Air Force.

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TYPE A {Modified)

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TYPE D {Modified) ? TYPEE

TYPE K, Ore Carrier

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DECLASSIFIED IAW DOD ?1,!E).W OF 3 MAY 1972, SUBJ:

nECLAS SI FICATI ON~ F W' RSGOl:{i) S

"'NI ZOB- J Supplentent 3 Division of Naval Intelligence

TYPE TL (Moclifiecl)

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TYPE TM (Moclifiecl)

STANDARD CLASSES OF JAPANESE MERCHANT SHIPS

TYPE A (Modified) . . . . . . . . Sugar Balcer Love

Gross tonnage: 6,670

Length, o. a.: 445'

Beam:

64'

TYPE C . . . . . . . . . . . . . . . . .. ?. Fox Tare Charlie

Gross tonnage: 2, 700

Length, o. a.: 321'

Beam:

45'

TYPE D.. . ............... Sugar Balcer Sugar

Gross tonnage: 1,900

Length, o. a.: 295'

Beam:

44'

TYPE D (Modified) . . . . . . . Sugar Charlie Love

Gross tonnage: 2,300

Length, o. a.: 310'

Beam:

49'

TYPE E. . . ...... . ..... .. Sugar Charlie Sugar

Gross tonnage: 830

Length,o.a.: 210'

Beam:

36'

TYPE K, Ore Cauier. .. ..... Fox Tare Charlie

Gross tonnage: 5,300

Length, o. a.: 410'

Beam:

59'

TYPE TL (Modified) . . . . . . . . Sugar Able Love

Gross tonnage: 10,000

Length, o. a .: 517'

Beam:

67'

TYPE TM . . . . . . . . . . . . . ???.. Sugar Able Item

Gross tonnage: 5,200

Length, o. a.: 410'

Beam:

59'

TYPE TM (Modified) . . . . . ? Sugar Able Sugar

Gross tonnage : 2,800

Length, o. a.: 325'

Beam:

50'

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TYPE A (Moclifiecl)

Sugar Baker Love

45- MKKMF

B

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..t. Type A (Mod ified)

Approximately 24 Type A and A (Modified) had been built b y Jul y 1944.

The following are believed to belong to one of these classes :

Large engines-aft cargo veseel with pronounced "economy" hull. Note

Batopaha Maru

5953

Oigawa Maru

6493

kingposts against bridge which is located almost amidships, small stack, and

Getsuyo Maru

6440

T aiten Maru

644 2

heavy stick masts centered in fore and after wells. One observed variation

Koyo Maru

6435

Tatebu Maru

6816

has wide cargo hatches extending three-fourths the beam of the ship. Ships of this class are under construction at Tokyo and have been observed being built near Nagasaki. No prefabrication of hull sections is apparent. Jap

Kyokuzan Maru Mitsuki Maru Nichiyo Maru

Nichizui Maru

6300 6440

6300 6584

Tatsunan Maru Tatsu-ura Maru Uyo Maru Yosan Maru

6417 6420

6376 6487

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Merchant Ship Card No. S 1007.

Nikkyu Maru

6529

Yosho Maru

6300

Nissho Maru

6008

Yowa Maru

6435

TYPE A (Modified)

Nisshun Maru TYPE A

6380

Yuzan Maru

6380

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Gross tonnage:

6,670

Disp. tonnage loaded: 9,720

Length, o. a.:

445'

Beam:

64'

Draft, loaded:

25.5'

Speed, normal cr. : 10 kts.

Machinery:

Steam turbine

SHP:

2,500 (oil)

2,000 (coal)

Cargo booms:

Twelve 5-ton

One 30-ton

Gross tonnage:

6,400

Disp. tonnage loaded: 9,300

Length, o. a.:

445'(?)

Beam:

58'

D raft, loaded:

25.5'

Speed , normal cr.: 12 kts.

Machin er y:

Reciprocating

I HP:

3,300

Cargo booms:

Eight 10-ton

Eight 15-ton

Two 25-ton

NOTE.-Early reports indicated use of steam tur bine and Diesel engines in this class.

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DECLASSIFIED I AW DCD u::;:c\0 OF 3 MAY 197g? .SI.IB.r:

DECLAS SI FICATI ON~ ~ ' :.:SC OI?::;).i

. ONI ZOB- J Supplement 3

D~vision of Naval In telligenc

B

45- MKMF

D

TYPE B

Sugar Baker Love

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Approximately 30 ships of the class are believed to have been built, including the following, some of which are possibly of engines am iqship construction.

Anbo i\Iaru Bichu i\Iaru Bizen Maru Chiyo Maru Fujishima Maru Kokuyo Maru Konan i\faru #1 N"aruo Maru Sainei Maru

4,523 4,667 4,667 4,700 4,930 4,667 4,558 4,823 4,916

Sankisan :\Iaru Shiranesan Maru Shiroganesan Maru Shoun Maru Shoyu Maru Tatebe Maru Toyu Maru Yamamiya Maru Yukigawa 7\'laru

4,776 4,739 4,739 4,399 4,408 4,519 4,532 4,440 4,502

Two new ships, one with a pronounced angular hull shape, fall within the probable length range for this class. No other sightings have been observed .

Gross tonnage:

4,400

Disp. tonnage loaded: 7,100

Length, o. a. :

410' (approx.)

Beam:

Draft, loaded:

24.3'

Speed, normal cr.: 12 kts.

Machinery :

Steam turbine

SHP:

2,400

Cargo booms:

Six 5-ton Four 10-ton One 30-ton

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TYPE A (Modified)

Sugar Baker Love

45- MKKMF

B

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Large engines-aft cargo ves~el with pronounced "economy" hull . Note kingposts against bridge which is located alrno~t amidships, small stack, and heavy stick masts centered in fore and after wells. One observed variation ha~ wide cargo hatches extending three-fourths the beam of the ship. Ships of this class arc under construction at Tokyo and have been observed being built near Nagasaki. No prefabrication of hull sections is apparent. Jap Merchant Ship Card No. S 1007.

TYPE A (Modified)

Gross tonnage:

6,670

Disp. tonnage loaded: 9,720

Length, o. a.:

445'

Beam:

64'

Draft, loaded:

25.5'

Speed, normal cr.: 10 kts.

Machinery:

Steam turbine

SHP:

2,500 (oil)

2,000 (coal)

Cargo booms:

Twelve 5-ton

One 30-ton

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? Type A (Modified)

Approximately 24 Type A and A (Modified) had been built by July 1944. The following are believed to belong to one of these classes:

Batopaha Maru

Getsuyo Maru Kovo Maru Kyokuzan Maru Mitsuki Maru Nichiyo Maru

Nichizui Maru Nikkyu Maru Nissho Maru

Nisshun Maru

5953 6440 6435

6300 6440

6300 6584 6529 6008

6380

Oigawa Maru Taiten Maru

Tatebu Maru Tatsunan Maru Tatsu-ura Maru Uyo Maru

Yosan Maru Yosho Maru Yowa Maru

Yuzan Maru

6493 6442 6816 6417 6420

6376 6487 6300 6435

6380

TYPE A

Gross tonnage:

6,400

Disp. tonnage loaded: 9,300

Length, o. a.:

445' (?)

Beam:

58'

Draft, loaded:

25.5'

Speed, normal cr.: 12 kts.

Yiachinery:

Reciprocating

HIP:

3,300

Cargo booms:

Eight 10-ton

Eight 15-ton

Two 25-ton

NorE.-Early reports indicated use of steam turbine and Diesel engines in this class.

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